I was watching the news tonight and thought this was interesting and possibly the wave of the future for security for employees working at airports.

Charlotte Douglas (CLT) is the first airport in the country to use eye scan technology, a device at four security checkpoints called eye pass to identify employees. The device captures an image of the iris and the software maps and records all of the detail onto a database. It can recognize if an employee is registered and where that employee is authorized to be.

Since no two humans iris' are the same the technology is said to be very precise. The eyepass is being used in addition to employee badges and will eliminate the threat of people using stolen or lost badges to gain access. The airport has spent about $20,000 to get it up and running.

Eye pass is using Charlotte Douglas as an example to show the Transportation Security Administration how well this system can work in hopes further airports will follow suit. So far Orr is sold on the new technology.

eyecolour (and therefore most contact lenses) indeed have no influence on the machine.

A similar system has been in operation at Schiphol (AMS) for several years now as a pilot (and now for frequent customers as part of a package of perks) and functions quite well.
Here the idea is to have a speedlane rather than use it for everyone (at least for now).